Hello.
Dependant 'pon what OS you are using; here are the current arrangements for .NET versions, when fully patched :-

WINDOWS 7
2.0.50727.4955
3.0.4506.4926
4.0.30319.1

VISTA SP2

2.0.50727.4209
3.0.4506.4037
4.0.30319.1

XP SP3

2.0.50727.3618
3.0.4506.2152
4.0.30319.1

It's worth bearing in mind that updates can take a couple of tries before they kick in.
Check for updates/ Install/Reboot.
Check again ; if any updates are found, reboot again before rescanning with psi.